I have a source from a SIRA series instrument that is performing very badly
in terms of linearity. There is a shift of as much as 8 per mille in the
46/44 ratio during a standard run with the gas depleting from the cold
finger of a dual inlet. With retuning of the source I can reduce this to ca.
5 per mille but no better. Does anyone have any hints regarding tuning,
filament change etc. which may help solve this problem or will I need to
change the complete source assembly.

I should add that I have 3 other similar sources all running on instruments
in my lab. and all behaving perfectly in terms of linearity. Moreover the
linearity is quite robust with respect to tuning, filament age etc. This
leads me to suspect that there may be a fundamental problem with the other
source that may only be resolved by repalcing the complete assembly!

Any hints. ideas will be gratefully accepted!

Paul




-----Original Message-----
From: Frank Pawellek <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Friday, February 13, 1998 1:43 PM
Subject: Re: turbo pumps


All,

..to add another opinion: we've been running Balzers turbo pumps on
four machines (06x and 180) for up to five years now, without any
breakdowns.

>From the very start the air cooling for all the pumps was replaced by
more efficient water cooling. In our opinion keeping the working
temperature low seems to be crucial for a long life of the pumps.

Regards,

Frank
+++++++++++++++++++++++++++++++++++++++++++++++
Frank Pawellek
Institut fuer Geologie
Lehrstuhl fuer Sediment- und Isotopengeologie
Ruhr-Universitaet Bochum
Universitaetsstrasse 150
44801 Bochum
Germany
Phone: +49-234-700-5458
Fax: +49-234-7094-571
+++++++++++++++++++++++++++++++++++++++++++++++